Thermophysical method for quantitative estimation of hydrate content in samples imitating bottom sediments

Gas hydrates in sediments can dissociate on heating, which causes a characteristic change in temperature over time. This can be used to detect hydrates and estimate their content. The geothermal method for gas hydrate prospecting consists in obtaining thermograms and defining regularities related to the presence of gas hydrates in the medium. The aim of this study was a quantitative estimation of hydrate content in sediments, based on data from repeated measurements of the temperature of a linear heat source (needle probe). The power of the source is chosen so that hydrate does not decompose in the first measurement but decomposes in the second. Afterward, we solve the optimization inverse problem of determination of the model parameters, one of which is a hydrate content. Experimental data on heating of the laboratory samples are processed, and hydrate contents are obtained with an accuracy of 30%. These values agree with independent estimates. The analytical solution of the axially symmetric problem of gas hydrate dissociation, based on the solution of the Stefan problem, is applied as a mathematical model for hydrate heating and decomposition in the sample.